Controlling the stoke of a Pneumatic Power Hammer.

[Steves Smithy]

Hi,  I'm very new hear and have found lots of good information.  I built a power hammer some time ago and used it as a treadle hammer with an electrical foot control on the control valve.  I'm not looking at the next phase which is to have it reciprocate and to control the exhaust outlets.  Up stroke will be controlled by a exhaust valve on the control valve and the Down stroke via a foot control, essentially a ball valve.

My question for the experts here about stroke control.   I have found the thread below but down of the pictures/videos are available.  It is an old post.   

I'm not sure how to set the Roller switches top and bottom and how these control the Cylinder When there is in effect 3 states. 

1. Up and needs to go extend

2. Down and needs to go retract

3. In the middle and we could be going up or down. 

I have looked at the the designs that have a 5/2 way switch (not lower switch) activated when the cylinder rises but this design is a momentary application of air flow and relies upon inertia to impact the anvil.   Perhaps I'm not understanding (probably since I know little in this space), but this design relies upon moving the sensor down/reducing the stroke when the pressure is reduced.  Hence I was researching having a top and bottom control switch.

Happy for someone to point me at a more recent post    

Thanks in advance.

[Frosty]

Welcome aboard Steve, glad to have you. If you put your general location in the header you'll have a better chance of meeting up with members living within visiting distance. Say someone who knows how to adjust your hammer and can show you in person. Nothing beats in person instruction for learning a thing.

Have you contacted the person who drew up the plans you used? If you developed plans from the fragments found everywhere on the internet you'll have problems, the only thing a person needs to be an expert on the web is a camera and connection. Your description lost me so all I can do is welcome you and assure you someone will be along to offer help.

Oh okay, I seem to be in a talky mood this morning. When I was researching power hammer builds I looked into and discarded most modern air hammers as just too complicated when a self contained is simpler and if you look at the early patents and drawings the valving is crazy simple. Then I got a deal on a 50lb little giant and shelved plans to build one.

Frosty The Lucky.

[Steves Smithy]

Thanks Frosty.  I'm in Melbourne Australia and yes I'm looking at Fragments on the net.  I'd like to think I could sift through the mire of stuff on the net but agree straying from a proven path is going to present some problems.  I've almost convinced myself to use a reed switch as this is a cheap component and I can then see how the exhausting is working and inertia on the down stroke.  If that doesn't work well then I'll have to design the limit switch solution which I have had some thoughts about how that would look over night.  

[Frosty]

Sure, been there got exhausted trying to figure out air hammers. You might want to take a look at some of the old patents, Bech and a couple others were dirt simple, easy spool valves made it work. 

If you want to know how a falling weight will work do the experiment hoist a weight as heavy as your hammer head and dies and let it fall on some hot steel. 

The problem I had with schemes using the exhaust as the control is I'm done with it by then and all it's good for is lifting the ram to the park position at the top of the stroke where the air escapes through a port in the shaft that opens at the top of the stroke. When it is cycling the switch valve opens just before the ram hits top so it's cushioned by the compressed air that drives it down into the work. The return valve trips just before impact ad up it goes on just enough pressure to lift it to top. 

Unfortunately I didn't like those plans much either and the commercial versions that work well don't sell the plans. There were a couple guys who made good air hammers, I wish I could remember the names, one is a current commercial build but the originator passed away a while ago. The name Krause or something like it keeps coming to mind but I don't recall details. 

Come on guys some of you old timers haven't taken shots to the head should remember a couple names or plans for sale. 

Frosty The Lucky.